Druckversion von:
http://www.geo.tu-freiberg.de/studenten/Baikal_2004/baikalexcursion/hydrogeology/overview/hydrolaccolith.HTM


Homepage TU BAF



Hydrogeology and Environmental Geology




Hydrogeology

Well types - Permafrost - Hydrolaccolith

Hydrolaccolith

A hydrolaccolith - also called pingo - is "a perennial frost mound consisting of a core of massive ice, produced primarily by injection of water, and covered with soil and vegetation" (Everdingen 2002). These pingos occur in continuous and discontinuous permafrost zones. The term is used to describe relatively large features with heights of 10 m or more and horizontal dimensions of more than 100 m. Most pingos are conical, somewhat asymmetric, and have a circular or oval base and a fissured top that may be cratered. The fissures and craters are the result of rupturing of the soil and vegetation cover during doming due to progressive development of the ice core (Everdingen 2002). In Russia they are formed on the bottom of dried or drying lake depressions and can reach 40 to 70 metres in height. In the presence of ground water the pingo appears with an ice core inside (Kotlyakov & Khromova 2002).
The investigated hydrolaccolith is situated west of Chernorud in the vicinity of the southern end of Maloe More in a valley the Kutschelga river drains. Its mound is approximately 3 to 4 metres high and 50 to 70 metres long. Its shape is more or less oval.


[Hydrolaccolith near Chernorud]

In the past Russian scientists made a drilling investigation. After that the active unfrozen layer has a thickness of 5 metres and consists primarily of clay and sand sediments and contains continental molluscs (Bukharov; personal comment). Because of the height over ground the laccolith was estimated to have a vertical extension of 50 to 100 metres, assuming the pingo has a water content of 30 percent and has no ice core. This estimation was derived from the expansion of ice at the prevailing gradient of temperature between water and ice. If the pingo consisted of ice, the vertical extension would be lower.

 

Everdingen, Robert van (ed) (2002) Multi-language glossary of permafrost and related ground-ice terms. Boulder, CO: National Snow and Ice Data Center/World Data Center for Glaciology. Side 56.

top




© B. Merkel <merkel@geo.tu-freiberg.de>, 29.11.2004, http://www.geo.tu-freiberg.de/studenten/Baikal_2004/baikalexcursion/hydrogeology/overview/hydrolaccolith.HTM